Why are Han Chinese so Racist & Xenophobia?

They few racists you talk about are the same as any other racist all over the world - they are racist and xenophobic because they are insecure, misinformed, scared, and feel threatened for some delusional reason. You can only feel sorry for them for having such a closed-mind, unworldly outlook and insular upbringing. It would be counter productive for you to ask such a racist question yourself.